Speakers

Abstract :

Presynaptic glutamate released by the certain type of neural activities can activate N-methyl-D-aspartate subtype of glutamate receptors (NMDARs) in postsynaptic dendrites, leading to induction of long-term potentiation (LTP) at many excitatory synapses. However, recent studies have also suggested possible actions of glutamate released from astrocytes in regulating synaptic functions, but the exact mechanisms are remained to be elucidated. Furthermore, NMDARs expressed at presynaptic axons are also thought to be involved in the process of LTP formation, but how presynaptic NMDARs regulate LTP induction remains to be clarified.

On the other hand, we also demonstrated that activation of presynaptic NMDARs at corticostriatal synapses by LTP-inducing stimuli can trigger activity-dependent secretion of brain-derived neurotrophic factor (BDNF), a member of a small family of secreted growth factor family protein. Both sustained axonal Ca2+ elevation and BDNF secretion were observed in response to the LTP-inducing stimuli, and these events were dependent on expression of functional NMDARs at presynaptic axons. These results demonstrate an equally important role of presynaptic NMDARs as that of postsynaptic NMDARs in LTP induction.